1. Field of the Invention
This disclosure relates to the field of newspaper presses. In particular, to the reboring of plate and blanket cylinder bores of existing newspaper presses to allow for the use of differently sized plate and blanket cylinders in the press.
2. Description of the Related Art
One natural resource which has gained a lot of attention recently is paper. In the last few years, paper recycling to reuse discarded paper has become a much more common activity and has become, for many, a big business. Further, as increased political pressure is brought to bear on paper use and paper recycling, paper has generally increased in price to accommodate increased recycling as well as to encourage more efficient use of new and recycled paper.
For a newspaper, the cost of the raw newsprint upon which to print the newspaper can be the most important consideration in whether the newspaper can survive in the marketplace and can be the most significant cost in operating the newspaper. In today's world, a newspaper must compete against radio, television, and the Internet for its share of advertiser's dollars spent towards reporting. As these other technologies are not bound by the use of paper, the cost of raw newsprint can determine whether or not a newspaper can compete and ultimately survive. Newsprint pricing regularly fluctuates on a quarterly basis which can often leave the newspaper uneasy about how the bottom line will look at the end of the year as even a small fluctuation can cancel out the profit margin built into the paper at the beginning of the year.
Most newspaper press lines running today were installed in the 1970's and 1980's before newsprint prices were inflated to the point they are today, when newsprint prices were more stable, and before the need to conserve paper was fully understood. When these presses were installed, the printed size of a page of a newspaper and therefore the size and design of the newspaper presses was generally selected to obtain a particular look of the newspaper or to allow a particular number of articles of a particular size to appear on various pages, instead of to preserve newsprint. For this reason, many of these presses utilize newspaper pages which are larger than their more modern counterparts. In the newspaper business, this difference in the newspaper size can result in a massive difference in profitability in the market.
In a newspaper, there are effectively two dimensions of the paper which can be controlled and which determine the amount of paper which is required to print each newspaper. A single sheet of newspaper (the pages which connect in the middle and printed on each side (four pages)) is generally a quadrilateral shape. A newspaper printing press will generally print newspaper pages on a roll of paper (or a paper web as it is often called). This web is printed with multiple sheets across the width of the paper roll (two or more sheets or eight or more pages) with these same pages repeated down the roll of paper. Alternatively, the press may print a first row of sheets, and then a second (or even third) row below that, before repeating the same pattern of rows. In this way, the newspaper sheets are essentially printed repetitively (serially) on the roll as it is unwound.
This design results because the press generally utilizes a continuously revolving cylinder as the printing surface to print the page. The cylinder has a length corresponding to the width of the paper roll and generally prints two or four sheets with each revolution (or half revolution) down the length of the roll. Different sheets are printed on a different paper roll (generally on a different press unit) with the newspaper comprising the appropriate sheets from a plurality of press units being properly arranged, cut and folded together.
As the pages are generally printed upright, to utilize a smaller horizontal dimension, a narrower paper roll is used and the press is set up to not utilize the entire length of the printing surface but only that which corresponds to the width of the roll (the ends of the printing cylinder are contacting only empty space as there is no paper to contact), Alternatively, a wider paper roll could be used utilizing more of the length of the printing cylinder and the system could be set up to print more sheets along the width of the paper. For example two and a half narrower sheets (10 pages) or even three narrower sheets (12 pages) may be printed along the width of a slightly wider roll of paper.
Because of the way the newspaper press is designed, while this horizontal dimension modification is fairly easy, it is difficult to change the height dimension of a newspaper or what is generally called the “cut-off” or “cut-off length.” The printing cylinder has a fixed circumference and because the cylinder endlessly rotates providing the repeated pattern of pages, the circumference of the cylinder corresponds to a predetermined number of complete pages. If the page length is shortened without changing the circumference of the cylinder, while the resultant newspaper size may be decreased, the cylinder still “prints” the section which had previously been used, it is just blank and is either still included in the resultant newspaper as simply a wide margin, or is somehow discarded as waste. Such a system does not save any paper.
In some dynamic presses, the printing cylinder could be modified dynamically so that a continuously changing pattern of repeating pages could be printed to allow for a printing cylinder to print a non-whole number of pages with each revolution, but such a dynamic system would be very expensive and difficult to operate making it unusable for most newspaper printing operations.
In order to alter the cut-off length of the paper in a conventional press line, either the pages must be made an equal subdivision of the existing page size (e.g. a print cylinder which has a circumference of one sheet can be made to print two sheets of half the original height) or the circumference of the printing cylinder must be changed. While the first of these concepts reduces the page size, it does not necessarily reduce the paper use as the newspaper will simply print twice as many half size pages. Further, a newspaper of half size often requires a completely different layout to be accepted by readers resulting in different problems. Therefore, the best solution is to have the press print the paper using a printing cylinder of a smaller diameter (and therefore a smaller circumference resulting in a decreased cut-off length).
While decreasing the printing cylinder diameter sounds like a relatively simple operation, with an existing press the printing cylinders and other components of the press are arranged to interact with each other by contact at their circumferential surfaces. If the printing cylinders diameters are simply decreased, necessary interactions will not occur and ink will not be correctly transferred to the paper web. Instead, cylinders of a decreased diameter generally require a closer, more compact arrangement where the axes of the cylinders are placed closer to each other.
Existing press units are large, heavy, and expensive pieces of machinery. The press unit principally comprises a large frame formed out of a material such as cast iron or steel with holes bored therethrough to enable the attachment of the various moveable components in a precise relation. Because of this design, switching to a smaller print roller currently requires completely replacing most, if not all of the existing press line as the press units generally cannot be modified to have mounts suitable for the new printing cylinders. While this is a viable solution in some cases, most of the time it is cost prohibitive as presses on a single press line (generally 6 or more printing units, a folder and related structures) would all need to be replaced simultaneously, which is a massive capital expense.
Many newspaper press lines in use today that were installed prior to the interest in paper reduction utilize a newspaper page height of 22″, 22¾″, or 23 9/16″. Today, new newspaper press lines are installing new presses that print at a 21″ length to save paper. These presses can save 8% to 10% of the newsprint over what an older press uses which is a gigantic savings in cost and materials. There is therefore a need in the art to have systems and methods for allowing an older press unit utilizing a first cut-off length, to be modified so as to have a new shorter cut-off length.